The field of the invention is diagnosis and genetic therapy for inherited diseases.
Hereditary haemorrhagic telangiectasia (HHT) or Osler-Weber-Rendu disease (OMIM #18730) is an autosomal dominant disorder characterized by multisystemic vascular dysplasia and recurrent haemorrhage. The disorder is named after the recurrent hemorrhage from vascular lesions, especially in the nasal mucosa and gastrointestinal tract, and for the presence of mucosal, dermal and visceral telangiectases. Pulmonary arteriovenous malformations (PAVMs) occur in approximately 20% of patients and are associated with serious complications including stroke and brain abscess. Other neurological manifestations include cerebral arteriovenous malformation, aneurysm and migraine headache.
Ultrastructural analyses of the vascular dysplasia seen in affected individuals have failed to demonstrate a unique pathological abnormality that might suggest the nature of the primary biochemical defect. Studies indicate that the dilated channels of telangiectases are lined by a single layer of endothelium attached to a continuous basement membrane (Jahnke, Arch. Ototaryngol. 91:262-265, 1970; Hashimoto and Pritzker, Oral Surg., Oral Med., Oral Pathol. 34:751-768, 1972). The earliest event in the formation of telangiectases appears to be dilation of post-capillary venules (Braverman et al., J. Invest Dermatol. 95:422-427, 1990). Eventually the dilated venules connect to enlarging arterioles through capillary segments which later disappear, creating direct arteriolar-venular connections. This sequence of events is associated with a perivascular mononuclear infiltrate (Braverman et al., J. Invest Dermatol. 95:422-427, 1990). Various explanations have been put forward to explain the angiodysplasia seen in HHT, including endothelial cell degeneration (Manafee et al., Arch. Ototaryngol. 101:246-251, 1975), defects in endothelial junctions (Hashimoto and Pritzker, Oral Surg., Oral Med., Oral Pathol. 34:751-768, 1972), lack of elastic fibers and incomplete smooth muscle cell coating of the vessels (Jahnke, Arch. Otolaryngol. 91:262-265, 1970), and weak connective tissue surrounding the vessel (Manafee et al., Arch. Otolaryngol. 101:246-251, 1975).
Genetic linkage for some HHT families was recently established to markers on chromosome 9q33-q34 (McDonald et al., Nature Genet. 6:197-204, 1994; Shovlin et al., Nature Genet. 6:205-209, 1994) and the locus was named OWR1. Genetic heterogeneity was established with the identification of some families clearly not linked to this region (Shovlin et al., Nature Genet. 6:205-209, 1994). The identification of key obligate recombinants in affected individuals allowed refinement of the OWR1 locus and placed the most likely candidate interval between D9S60 and D9S61 in a 2 centiMorgan (cM) interval (Shovlin et al., Nature Genet. 6:205-209, 1994).